Effects of ball-milling on the preparation of LiFePO4 cathode material for lithium-ion batteries

Olivine LiFePO4 / C composite powders were synthesized by solid-state reaction with wet ball-milling procedure. The powder properties and the electrochemical characteristics of the prepared samples were investigated in comparison with those samples obtained by dry ball-milling. The crystal structure and the electrochemical performance were characterized by XRD, SEM, laser particle-size distribution measurement and electrochemical performance testing. The olivine LiFeP04 obtained from wet ball-milling shows a maximum discharge capacity of 134.9 mAh - g-1 at the C/5 rate. The composite also displays a better rate capability, a higher charge-discharge capacity and a more stable cycle-life than those samples from dry ball-milling. The improved electrode performance of samples by wet ball-milling originates mainly from very fine particles of sub-micron size and a homogeneous surface morphology. These powder characteristics increase the surface area of LiFePO4 particles and maximize the contact area with the conductor additives, resulting in enhanced electrochemical performance.